1. Technical Field
This invention relates to exercise machines for abdominal muscles and more, particularly to exercise machines in which the lower legs are supported by a leg support that utilizes a rolling, gliding, or sliding mechanism.
2. Description of Related Art
Traditional abdominal exercises, such as sit-ups are known to cause overload to the spine and neck and can easily cause injury when sitting up from a prone position to a sitting position. To correct this problem, many devices and exercises have been created in an attempt to develop and maintain the abdominal muscles. Unfortunately these devices and exercises often produce results which do not necessarily strengthen the abdominal muscles but strengthen the hip and thigh muscles attached to the lumbar spine area and to the rear of the pelvis and hip bones. When such muscles contract not only does the rectus muscle of the abdomen work with little effort but the other muscles rotate the pelvis forward thus creating the occurrence of increased lower back pain which contributes to poor mechanical alignment and undesirable upright posture of the exerciser.
For example, abdominal exercises that use arm slings and the person hanging from a bar are only beneficial to advanced athletes that are able to perform the exercise effectively. However, even when performed effectively, the back is extremely overloaded and the hip-flexors handle much of the load creating a risk of injury.
Also, lower abdominal exercises utilizing leg raises or reverse crunches where the knees are raised to the chest while the body is suspended vertically, supported only by arms or elbows, are strenuous on the lower back and offer minimal back support. These types of exercises are especially bad due to excessive strain on the back caused by lifting the knees to the chest. Furthermore, a significant number of people who do this type of abdominal exercise become injured with continued use.
Also, some exercise machines concentrate on cardio training with too little resistance thereby producing semi-effective strength training with very limited results. For example, exercise machines similar to the AB LOUNGE or AB SCISSOR provide more isolation than the above abdominal exercise but do not provide enough resistance because the exercise motions performed with these devices do not provide a resistance that is consistent with strength training.
In addition, exercise machines similar to the AB DOLLEY or AB SLIDE are effective for upper abdominal muscles and upper torso but not for lower abdominals. Also, exercises using these types of devices are difficult and dangerous for two reasons: first resistance is concentrated downward by gravity making isolation on the abdominal muscles impossible, as the entire upper torso, front and back muscles, and arms are needed to handle the load; and second, the user's back is forced into an ergonomically unfriendly angle with the upper body which is operating too low in conjunction with the lower body. Such a position is uncomfortable, awkward and can cause injury.
What is needed is an abdominal exerciser that will isolate the upper and lower abdominal muscles with true strength conditioning to change the shape of the overall abdomen muscle structure without compromising safety or support for the back. It would be beneficial if the apparatus could enable a user to execute the abdominal exercise in a biometrically neutral position, minimizing or eliminating back and neck strain. It would also be beneficial if the user could perform an upper abdominal crunch simultaneously with a controlled and supported reverse crunch. It would further be beneficial if the apparatus could allow the user to hold either the upper or lower crunch in a fully contracted “isometric” position while continuing with the opposite crunch rendering a dynamically concentrated isolation of the abdominal muscles.